[css-syntax] keeping the indent level under control in modern CSS with `@layer`, `@scope`, nesting, ...

[romainmenke]

Example :

@layer components {
	@scope (.my-component) to (.child-component-slot > *) {
		.my-component {
			color: cyan;
			padding: 0.5rem;

			&:hover {
				color: blue;
			}

			@media (min-width: 768px) {
				padding: 1rem;
			}
		}
	}
}

This is starting to look a bit like the callback hell from JS :

getBeef("foo", (rawBeef) => {
	sliceBeef(rawBeef, (slicedBeef) => {
		cookBeef(slicedBeef, (cookedBeef) => {
			serveBeef(cookedBeef, (servedBeef) => {
				console.log(servedBeef);
			});
		});
	});
});

---

Some of this can be externalized by adding bits of it to @import :

@import "my-component.css" layer(components);

But this isn't always possible or good practice for maintainable code.
Often the reason for wrapping code in an at-rule is tightly coupled with the code that is wrapped.

---

Using nesting is a choice and authors can choose not to nest.

---

@when does not help here because it wasn't designed for @layer, @scope, @container, ...
Personally I don't think @when should be shipped at all because it doesn't solve the issue fully. Maybe I am wrong here and @when could be used for all at rules?

---

The underlying issue is that at-rules can only be "combined" or "stacked" by nesting them. With the introduction of new at-rules and nested CSS source code will only become more heavily nested and less readable.

I don't have a concreet proposal for a syntax that could help here.
I do however think it is something that should be explored.

[bleper]

🧐

// no-spaghetti.css

@rules
{  @layer (components)
;  @scope (.my-component)
;  @boundary (.child-component-slot > *)
;  @selectors (.my-component)
;  @declarations
   {  color : cyan
   ;  padding : .5rem
}  @nest 
   {  @selectors (&:hover)
   ;  @declarations
      {  color : blue
}} @nest 
   {  @media (min-width: 768px)
   ;  @declarations
      {  padding : 1rem
}}}

🤔🤔🤔

/*\-------+
 # WHATSS #
 +-------\*/

@rules --component {
   @layer (components);
   @scope (.my-component);
   @boundary (.child-component-slot > *);
   @selectors (.my-component);
   @declarations --component;
   @nest --component-hover;
   @nest --component-response}

@declarations --component {
   @properties
      (color),
      (padding);
   @values
      (cyan),
      (.5rem)}

@nest --component-hover {
   @selectors (&:hover);
   @declarations --component-hover}

@declarations --component-hover {
   @properties (color);
   @values (blue)}

@nest --component-response {
   @media (min-width: 768px);
   @declarations --component-response}

@declarations --component-response {
   @properties (padding);
   @values (1rem)}